Field of the Invention
The invention generally relates to digital-to-analog converters (DAC), and more particularly, to methods of configuring a high-voltage tolerance circuit in the DAC to make sure that the DAC-for-28 nanometer (nm) manufacturing process can operate normally with a high-power source voltage.
Description of the Related Art
A television (TV)/Cathode Ray Tube (CRT) video digital-to-analog converter (DAC) is usually realized by the current-steering DAC structure, where it can output two kinds of analog signals: one for the TV mode and one for the CRT mode. The full-scale voltages for the TV mode and the CRT mode are 1.33 V and 0.69 V, respectively.
In 45-nanometer (nm) manufacturing process, the transistor can support a power-source voltage of up to 2.3V. Therefore, when the output voltage for the full-scale voltage of the TV mode is 1.33V, the traditional DAC can achieve a higher linearity. However, as the size of the manufacturing process technology is reduced to 28 nanometers (nm), the voltage endurance of the transistor is reduced to 1.8V. In these cases, when the traditional DAC is utilized to work with a full-scale voltage (or one that is approximate to that of the full-scale voltage) of the TV mode, the DAC cannot achieve the linearity required by the product standards, and as a result, the applications of the DAC will be limited.